This research program project includes the following studies: 1. Normal development of the nervous system in humans to be carried out on the embryos and fetuses of the Carnegie Collection and on others that have been collected, and including detailed studies of: (a) the normal sequence of development of the central and peripheral nervous system, skull, vertebrae, and limbs in staged embryos, so as to provide an accurate morphological base for the analysis of congenital defects and malformations. (b) The growth and maturation of the fetal nervous system, skull, vertebrae, and limbs, especially with respect to the downgrowth of tracts such as the pyramidal through highly organized and functioning brain stem and spinal cord. Particular attention will be paid to correlation with congenital defects and malformations. 2. Normal development of the nervous system in non-human primates using the material of the Carnegie Collection and the California Primate Research Center, and including studies of normal development of embryonic and fetal brain, including interpeduncular nucleus and eye. 3. Teratological studies: These were carried out at the California Primate Research Center: a) experimental teratological studies focusing on anencephaly, myelomeningocoele and craniofacial defects, and b) studies of the mechanisms of teratogenesis in the CNS rhesus monkey embryos are presently being completed. 4. Completion of the computerized catalogue of prenatal primate material will be undertaken. 5. Clinicopathological studies. As in the past, clinicopathological studies of human congenital defects and malformations and morphological correlations with experimental studies will be carried out at the UCD Medical Center in Sacramento.